1. Field of the Invention
The invention relates to new flame-retardant and infusible fibers made from melamine-aldehyde resins.
2. Description of the Prior Art
Recently, in order to prevent fire and disasters, it has been desirable that even ordinary textile goods for general use such as clothes, bedding, curtains, mattings and covers, etc., have flame-retardant properties. If non-flame-retardant textile goods are exposed to fire, the flames will propagate further and may result not only in heavy property loss but also may cause bodily damage or even death. Therefore, to prevent fires and related accidents, the demand for non-combustible or flame-retardant textiles has increased in recent times. In addition to flame-retardant properties, it is also desirable that such textiles be thermally infusible and have low thermal shrinkage.
If textile goods are thermally fusible or highly thermally shrinkable, and are exposed to fire, the flames may spread therethrough very rapidly in view of the spaces caused by fusion or shrinkage near the fire, possibly resulting in bodily damage. Moreover, one may receive burns by contact with the molten polymers or the hot contracted fibers. Therefore, the infusibility of the fibers is of course considered to be an important safety factor.
Furthermore, from the standpoint of preventing disasters in a fire, it is desirable that such textile goods generate as small an amount of smoke or poisonous gas as possible when heated. Of course, the generation of large amounts of smoke and poisonous gas will surely prevent rapid escape and, more significantly, there is a danger of suffocation in such circumstances.
Almost all well-known fibers which are used broadly in various fields for general use, except such special fibers as inorganic fibers, carbon fibers and phenol resin fibers, are very flammable and therefore dangerous. Even if a fiber is flame-retardant, it is normally fusible or thermally shrinkable, or may generate large quantities of smoke and poisonous gas. Thus, given these properties, known flame-retardant fibers are deficient in preventing fire and disasters.
Although inorganic and carbon fibers have desirable flame-retardant properties, they are not generally used in textile goods in view of their many defects in properties necessary for general use, such as their low spinnability and weaveability (due to their low strength and flexibility), large thermal conductivity, low hygroscopicity, bad feel and low dyeability. Moreover, although phenol resin fibers have been attracting attention for their flame-retardant properties, it is difficult to spin and weave such fibers in view of their low strength (i.e., tenacities of 1 - 1.5 g/d), they have a yellow-brown color and are quickly colored by the sun even after being bleached almost white, and further, they have a very poor dyeability. Such properties are totally unacceptable for general use, and therefore phenol resin fibers have not been broadly used in the textile art.
There is a need, therefore, for fibers which are both flame-retardant and have the other properties required for general use in textile goods.